As for determining which animals have been strangled and not drained of their blood, we must understand that the focus was on the quantity of blood remaining in the meat of the animal. It was not the fact that the animal was strangled that kept it from being eaten, but the fact that it was never drained of its blood.
The Eocene constitutes the middle part of the Paleogene period (65-23 million years ago), preceded by the Paleocene and succeeded by the Oligocene epoch (34-23 million years ago); all of these periods and epochs were part of the Cenozoic Era (65 million years ago to the present).
This period is called the Palaeozoic era, and lasted from 540 million years ago until 245 million years. The next period in the Earth's development started 245 million years ago and lasted until 65 million years ago, at which point about 80 to 90% of all animals were killed, with the main exception being birds.